U.S. patent number 7,594,566 [Application Number 12/089,447] was granted by the patent office on 2009-09-29 for lock device, transmission/drive unit containing such a lock device, and method for manufacturing such a transmission/drive unit.
This patent grant is currently assigned to Robert Bosch GmbH. Invention is credited to Peter Klobes, Ulrich Rettmar.
United States Patent |
7,594,566 |
Rettmar , et al. |
September 29, 2009 |
Lock device, transmission/drive unit containing such a lock device,
and method for manufacturing such a transmission/drive unit
Abstract
Blocking apparatus, as well as a gearbox drive unit containing
such a blocking apparatus, as well as a method for production of a
gearbox drive unit such as this for blocking any rotary movement of
a shaft (14) with respect to a housing (16) of the gearbox drive
unit (10), having a first blocking element (32) which can rotate
and having a second blocking element (34) which can be moved with
respect to the first blocking element (32) by means of at least one
electromagnet (44) and at least one return element (42), with the
blocking elements (32, 34) engaging with one another in an
interlocking form in the axial direction in the blocked state, and
with at least one acoustic damping element (28) being arranged
axially between the interlock (85) and the electromagnet (44).
Inventors: |
Rettmar; Ulrich (Buehlertal,
DE), Klobes; Peter (Bietigheim, DE) |
Assignee: |
Robert Bosch GmbH (Stuttgart,
DE)
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Family
ID: |
37720081 |
Appl.
No.: |
12/089,447 |
Filed: |
November 15, 2006 |
PCT
Filed: |
November 15, 2006 |
PCT No.: |
PCT/EP2006/068483 |
371(c)(1),(2),(4) Date: |
April 07, 2008 |
PCT
Pub. No.: |
WO2007/062981 |
PCT
Pub. Date: |
June 07, 2007 |
Prior Publication Data
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Document
Identifier |
Publication Date |
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US 20080251329 A1 |
Oct 16, 2008 |
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Foreign Application Priority Data
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Nov 29, 2005 [DE] |
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10 2005 057 239 |
Apr 18, 2006 [DE] |
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10 2006 018 094 |
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Current U.S.
Class: |
188/171; 188/265;
310/77 |
Current CPC
Class: |
F16D
63/006 (20130101); F16D 65/0006 (20130101); H02K
7/1023 (20130101); F16D 2121/22 (20130101); H02K
7/1166 (20130101) |
Current International
Class: |
H02K
49/00 (20060101) |
Field of
Search: |
;188/161-164,171,265
;192/84.941 ;310/77,93 |
References Cited
[Referenced By]
U.S. Patent Documents
Foreign Patent Documents
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297 06 124 |
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Jun 1997 |
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DE |
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1 320 175 |
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Jun 2003 |
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EP |
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2588702 |
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Apr 1987 |
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FR |
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2785656 |
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May 2000 |
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FR |
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2 258 702 |
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Feb 1993 |
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GB |
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4-98858 |
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Mar 1992 |
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JP |
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10-19065 |
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Jan 1998 |
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JP |
|
Primary Examiner: Schwartz; Christopher P
Attorney, Agent or Firm: Striker; Michael J.
Claims
What is claimed is:
1. A locking device (30) for preventing a rotating motion of a
shaft (14) in relation to a housing (16) of a transmission/drive
unit (10), said locking device (30) comprising a first locking
element (32); a second locking element (34) that is movable in
relation to the first locking element (32) by an electromagnet (44)
and at least one return element (42) so that in a locked state the
locking elements (32, 34) engage with each other in an axial
direction (15) by means of a form-locking engagement (85); at least
one acoustic damping element (28) axially situated between the
electromagnet (44) and the form-locking engagement (85); and an
additional acoustic damping element (29) axially situated between
the first locking element (32) and the second locking element (34)
to reduce noise generation as the locking elements (32, 34) engage
with each other in said form-locking engagement (85).
2. The locking device (30) as recited in claim 1, wherein said at
least one acoustic damping element (28) comprises a damping ring
(90) that damps in the axial direction (15), said damping ring (90)
has a circular, D-shaped, rectangular or X-shaped cross section,
and said damping ring (90) is situated in a groove (92) located on
an axial side (87) of the electromagnet (44).
3. The locking device (30) as recited in claim 1, wherein said at
least one return element (42) comprises an annular spring (43).
4. The locking device (30) as recited in claim 3, wherein said
annular spring (43) is a conical spiral spring (99) that
encompasses the shaft (14).
5. The locking device (30) as recited in claim 1, wherein said at
least one acoustic damping element (28) is made of plastic and has
an axial profiling (101) that provides a contact surface (100) for
the second locking element (34).
6. The locking device (30) as recited in claim 1, wherein said at
least one acoustic damping element (28) comprises a composite plate
(38) integrated into the second locking element (34) and wherein
said composite plate (38) comprises a viscoelastic plastic layer
(39) and at least one metal plate (40).
7. The locking device (30) as recited in claim 6, wherein the
second locking element (34) comprises a base plate (94) embodied as
the composite plate (38), onto which an axial gearing (82, 84) is
injection-molded to provide said form-locking engagement (85) for
form-locking said second locking element (34) with said first
locking element (32).
8. The locking device (30) as recited in claim 1, wherein the
second locking element (34) is provided with axial holes (81) and
the electromagnet (44) has axial guide pins (79) formed on an axial
side (87) of the electromagnet (44) and arranged to engage in the
axial holes (81) of the second locking element (34) in order to
axially guide the second locking element (34).
9. A locking device (30) for preventing a rotating motion of a
shaft (14) in relation to a housing (16) of a transmission/drive
unit (10), said locking device (30) comprising a first locking
element (32); a second locking element (34) that is movable in
relation to the first locking element (32) by an electromagnet (44)
and at least one return element (42) so that in a locked state the
locking elements (32, 34) engage with each other in an axial
direction (15) by means of a form-locking engagement (85); and at
least one acoustic damping element (28) axially situated between
the electromagnet (44) and the form-locking engagement (85);
wherein said at least one acoustic damping element (28) is fixed by
said at least one return element (42) to an axial side (87) of the
electromagnet (44) or to the second locking element (34); and
wherein said at least one return element (42) is an annular spring
(43).
10. The locking device (30) as recited in claim 9, wherein said
annular spring (43) is a conical spiral spring (99) that
encompasses the shaft (14).
11. The locking device (30) as recited in claim 9, wherein said at
least one acoustic damping element (28) comprises a damping ring
(90) that damps in the axial direction (15), said damping ring (90)
has a circular, D-shaped, rectangular or X-shaped cross section,
and said damping ring (90) is situated in a groove (92) located on
said axial side (87) of the electromagnet (44).
12. The locking device (30) as recited in claim 9, wherein said at
least one acoustic damping element (28) is made of plastic and has
an axial profiling (101) that provides a contact surface (100) for
the second locking element (34).
13. The locking device (30) as recited in claim 9, wherein said at
least one acoustic damping element (28) comprises a composite plate
(38) integrated into the second locking element (34) and wherein
said composite plate (38) comprises a viscoelastic plastic layer
(39) and at least one metal plate (40).
14. The locking device (30) as recited in claim 13, wherein the
second locking element (34) comprises a base plate (94) embodied as
the composite plate (38), onto which an axial gearing (82, 84) is
injection-molded to provide said form-locking engagement (85) for
form-locking said second locking element (34) with said first
locking element (32).
15. The locking device (30) as recited in claim 9, wherein the
second locking element (34) is provided with axial holes (81) and
the electromagnet (44) has axial guide pins (79) formed on said
axial side (87) of the electromagnet (44) and arranged to engage in
the axial holes (81) of the second locking element (34) in order to
axially guide the second locking element (34).
16. A locking device (30) for preventing a rotating motion of a
shaft (14) in relation to a housing (16) of a transmission/drive
unit (10), said locking device (30) comprising a first locking
element (32); a second locking element (34) that is movable in
relation to the first locking element (32) by an electromagnet (44)
and at least one return element (42) so that in a locked state the
locking elements (32, 34) engage with each other in an axial
direction (15) by means of a form-locking engagement (85); and at
least one acoustic damping element (28) axially situated between
the electromagnet (44) and the form-locking engagement (85);
wherein said at least one return element (42) comprises an annular
spring (43) and said at least one acoustic damping element (28)
comprises an elastic sheath (112) on said annular spring (43).
17. The locking device (30) as recited in claim 16, wherein said
annular spring (43) is a conical spiral spring (99) that
encompasses the shaft (14).
18. The locking device (30) as recited in claim 16, wherein said at
least one acoustic damping element (28) comprises a damping ring
(90) that damps in the axial direction (15), said damping ring (90)
has a circular, D-shaped, rectangular or X-shaped cross section,
and said damping ring (90) is situated in a groove (92) located on
an axial side (87) of the electromagnet (44).
19. The locking device (30) as recited in claim 16, wherein said at
least one acoustic damping element (28) comprises a plastic
material and has an axial profiling (101) that provides a contact
surface (100) for the second locking element (34).
20. The locking device (30) as recited in claim 16, wherein said at
least one acoustic damping element (28) comprises a composite plate
(38) integrated into the second locking element (34) and wherein
said composite plate (38) comprises a viscoelastic plastic layer
(39) and at least one metal plate (40).
21. The locking device (30) as recited in claim 20, wherein the
second locking element (34) comprises a base plate (94) embodied as
the composite plate (38), onto which an axial gearing (82, 84) is
injection-molded to provide said form-locking engagement (85) for
form-locking said second locking element (34) with said first
locking element (32).
22. The locking device (30) as recited in claim 16, wherein the
second locking element (34) is provided with axial holes (81) and
the electromagnet (44) has axial guide pins (79) formed on an axial
side (87) of the electromagnet (44) and arranged to engage in the
axial holes (81) of the second locking element (34) in order to
axially guide the second locking element (34).
23. A locking device (30) for preventing a rotating motion of a
shaft (14) in relation to a housing (16) of a transmission/drive
unit (10), said locking device (30) comprising a first locking
element (32); a second locking element (34) that is movable in
relation to the first locking element (32) by an electromagnet (44)
and at least one return element (42) so that in a locked state the
locking elements (32, 34) engage with each other in an axial
direction (15) by means of a form-locking engagement (85); at least
one acoustic damping element (28) axially situated between the
electromagnet (44) and the form-locking engagement (85); and a lock
housing (52) that has a cylinder wall (35) and a plug (58) on one
side of the cylinder wall (35); wherein said cylinder wall (35) is
embodied as a pole tube (33) of the electromagnet (44) and is
provided with a radial recess (76) on another side of the cylinder
wall (35) that is opposite said one side to compensate for missing
magnetic flux in the vicinity of the plug (58).
24. The locking device (30) as recited in claim 23, wherein said at
least one return element (42) comprises an annular spring (43).
25. The locking device (30) as recited in claim 24, wherein said
annular spring (43) is a conical spiral spring (99) that
encompasses the shaft (14).
26. The locking device (30) as recited in claim 23, wherein said at
least one acoustic damping element (28) comprises a damping ring
(90) that damps in the axial direction (15), said damping ring (90)
has a circular, D-shaped, rectangular or X-shaped cross section,
and said damping ring (90) is situated in a groove (92) located on
an axial side (87) of the electromagnet (44).
27. The locking device (30) as recited in claim 23, wherein said at
least one acoustic damping element (28) is made of plastic and has
an axial profiling (101) that provides a contact surface (100) for
the second locking element (34).
28. The locking device (30) as recited in claim 23, wherein said at
least one acoustic damping element (28) comprises a composite plate
(38) integrated into the second locking element (34) and wherein
said composite plate (38) comprises a viscoelastic plastic layer
(39) and at least one metal plate (40).
29. The locking device (30) as recited in claim 28, wherein the
second locking element (34) comprises a base plate (94) embodied as
the composite plate (38), onto which an axial gearing (82, 84) is
injection-molded to provide said form-locking engagement (85) for
form-locking said second locking element (34) with said first
locking element (32).
30. A transmission/drive unit (10) comprising a housing (16), a
drive shaft (14) supported in the housing (16) and a locking device
(30) according to claim 29, in which the first locking element (32)
is rotatable in relation to the housing (16).
31. The locking device (30) as recited in claim 23, wherein the
second locking element (34) is provided with axial holes (81) and
the electromagnet (44) has axial guide pins (79) formed on an axial
side (87) of the electromagnet (44) and arranged to engage in the
axial holes (81) of the second locking element (34) in order to
axially guide the second locking element (34).
32. The locking device (30) as recited in claim 23, wherein said
lock housing (52) has a thrust washer (60) and the first locking
element (32) rests axially against said thrust washer (60) of the
lock housing (52).
33. A method of manufacturing a transmission/drive unit (10),
wherein said transmission/drive unit comprises a housing (16), a
drive shaft (14) supported in the housing (16) and a locking device
(30); wherein the locking device (30) comprises a first locking
element (32), a second locking element (34) that is movable in
relation to the first locking element (32) by an electromagnet (44)
and at least one return element (42) so that in a locked state the
locking elements (32, 34) engage with each other in an axial
direction (15) by means of a form-locking engagement (85), at least
one acoustic damping element (28) axially situated between the
electromagnet (44) and the form-locking engagement (85), and a lock
housing (52) that has a cylinder wall (35) and a plug (58) on one
side of the cylinder wall, said cylinder wall (35) being embodied
as a pole tube (33) of the electromagnet (44) and being provided
with a radial recess (76) on another side of the cylinder wall (35)
that is opposite from said one side to compensate for missing
magnetic flux in the vicinity of the plug (58); wherein said method
comprises the steps of: a) attaching the locking device (30) to the
housing (16) of the transmission/drive unit (10); and then b)
inserting the shaft (14) together with a drive element (66) in a
central recess (64) provided in the first locking element (32) in a
play-encumbered form-locked engagement.
34. The method as recited in claim 33, further comprising testing
the locking device (30) as a separate unit enclosed by the lock
housing (52) prior to attaching the locking device (30) in the
housing (16) and placing the at least one acoustic damping element
(28) in the lock housing (52) with the locking elements (32, 34)
prior to the testing.
Description
CROSS-REFERENCE
This is the U.S. National Stage of PCT/EP 2006/068483, filed on
Nov. 15, 2006, in Europe. The invention described and claimed
herein below is also described in German Patent Applications 10
2005 057239.1 and 10 2006 018094.1, filed in Germany on Nov. 29,
2005 and Apr. 18, 2006 respectively. The aforesaid German Patent
Applications provide the basis for a claim of priority of invention
for the invention claimed herein below under 35 U.S.C.
119(a)-(d).
BACKGROUND OF THE INVENTION
1. The Field of the Invention
The invention relates to a locking device with two locking elements
situated in movable fashion in relation to each other, a
transmission/drive unit containing such a locking device, and a
method for manufacturing such a transmission/drive unit according
to the preambles to the independent claims.
2. Description of the Related Art
EP 1 320 175 A2 has disclosed a drive- and/or braking device in
which a brake unit is situated inside a housing that encloses an
electric motor. The brake unit has a brake disc and a brake element
that can be electromagnetically pressed against each other in a
frictionally engaging fashion. The brake element here is attached
to the housing of the electric motor in a rotationally and axially
fixed fashion while the brake disc is situated in an axially
movable fashion on the rotatably supported armature shaft of the
electric motor.
A braking device embodied in this way has the disadvantage that a
large number of tolerances must be compensated for during assembly
of the drive unit because during the assembly, the brake element is
preinstalled directly on the housing and the brake disc is
preinstalled on the armature shaft and only after this are they
assembled and adjusted in relation to each other. In addition, the
frictional engagement between the two brake discs is very
susceptible to wear and other influences such as dirt, carbon dust,
grease, and abrasion phenomena, which is why in EP 1 320 175 A2,
the housing of the electric motor also has to be sealed in a
watertight, airtight, and dust-tight fashion. In addition, such a
device produces relatively loud noise when actuated, which can be
unpleasant to the occupants of a motor vehicle.
SUMMARY OF THE INVENTION
It is an object of the present invention to provide an improved
locking device and an improved transmission/drive unit containing
the locking device, which do not have the above-described
disadvantages of the prior art devices.
The transmission/drive unit according to the present invention and
the locking device situated therein as well as the method for
manufacturing such a transmission/drive unit have the advantage
that embodying the locking device as an independent, completely
installable module significantly reduces the assembly cost for such
a transmission/drive unit. In this case, it is not necessary for
there to be a high degree of assembly precision of the drive
element on the shaft in relation to the locking device and a high
degree of positioning precision of the locking device in the
housing of the transmission/drive unit. The axial tolerances (air
gap) between the locking elements can be maintained at
significantly less expense with the separate manufacture and
independent function testing of the locking device. Due to the
embodiment of an axial form-locked engagement between the two
locking elements, the locking device is much less sensitive to dirt
and grease, moisture, or carbon dust. The minimal wear and abrasion
of the locking elements extends the longevity and long-term load
capacity of the locking device. Due to the embodiment of the axial
form-locked engagement between the two locking elements, for
example in the form of an axial gearing (radially oriented flutes
with teeth engaging in them), the locking device is also suitable
for use in motor vehicles in which increased vibration- and
agitation stresses occur. By contrast with the arrangement of brake
discs, the present invention is not sensitive to a resonance
frequency of the spring/mass system that is excited by the
vibrations in the vehicle. The placement of a damping element
between the electromagnet and the second locking element can
effectively suppress the excitation of structure-borne noise as the
lock is being released.
Advantageous modifications of the device and method according to
the independent claims are possible by means of the defining
characteristics disclosed in the dependent claims. If the damping
element 28 is embodied in the form of a ring encompassing the
shaft, then the second locking element is damped uniformly over the
entire circumference upon impact with the electromagnet. It is
advantageously possible for the ring to be embodied of one piece
and, due to its expansion, to be simply fastened over the entire
circumference.
In order to effectively suppress the structure-borne noise, in the
best-case scenario, the damping element is embodied of a plastic,
preferably an elastomer, which can effectively absorb the
structure-borne noise over a large temperature range.
If the damping element is embodied as an O-ring or D-ring, then it
can be simply pressed into a corresponding groove on the
electromagnet or on the second locking element. The cross-section
of the damping ring in this case can be circular, D-shaped,
X-shaped, rectangular, or the like so that the axial movement of
the second locking element is braked in relation to the magnet.
The electromagnet has an inner pole on which a coil element is
supported, the two of which combine to form an axial end surface to
which the damping element can be affixed.
Alternatively, however, it is also possible to fasten the damping
element to the opposite axial surface of the second locking
element.
In order to reduce an excitation of structure-borne noise during
the closing of the locking device as well, at least one additional
damping element is situated between the two locking elements and
brakes the impact of the second locking element against the first
locking element brought about by the return spring.
The axial end surface of the electromagnet can advantageously have
a rounded region formed onto it, which the second locking element
strikes against when the locking device is released. Through the
formation of the rounded region, the second--deforming--locking
element comes into contact with the electromagnet in a continuous
fashion, thus significantly reducing the excitation of
structure-borne noise.
It is particularly advantageous to embody the damping element out
of a plastic film, in particular embodied as an adhesive film, that
can be glued in a self-adhesive way to the two axial end
surfaces.
In a preferred embodiment, an annular spring presses the annular
damping element against the end surface of the electromagnet or of
the second locking element. In this case, it is advantageous if the
return spring, which is provided for the second locking element
anyway, can be simultaneously used for the fixing of the damping
element.
In an alternative embodiment, an elastic damping element is formed
directly onto the return spring, for example by being injection
molded onto it. This elastic damping element can be embodied in the
form of a sheath around one or more coils of a spiral spring or in
the form of a shaped part. This eliminates the need for a separate
fastening process for the damping element.
If a conical spiral spring is used as the annular spring, then this
assures a clean axial guidance of the second locking element
without requiring additional space in the axial direction. In a
particularly favorable embodiment, the spiral spring can rest
against an axial offset between the inner pole and the coil
element, thus fixing the spiral spring in the radial direction.
If the inner pole forms such an axial offset with the coil element,
then the damping element, embodied in the form of a hat-shaped cap,
can advantageously be placed over the inner pole and the coil
element so that the hat-shaped cap rests radially against the axial
offset.
Preferably, such a damping element is manufactured out of Teflon
and optionally has an axial profile as a stop surface, which
acoustically damps the stopping of the second locking element.
In an alternative embodiment, the damping element is integrated
into the second locking element. To this end, preferably a
composite material is used as a base component for the second
locking element, which component is composed of at least one
plastic layer and one metal plate. The fixed bonding of the
viscoelastic plastic layer to the metal plate effectively
suppresses excited structure-borne vibrations in the acoustic
range.
The second locking element in this case is particularly simple to
manufacture in that an axial form-locked engaging element is
injection molded directly onto a baseplate made of the composite
sheet and engages with the first control element.
In this case, the base part of the second locking element is
simultaneously embodied as an armature plate serving as the
magnetic yoke for the electromagnet. Since the composite plate has
at least one or two metal plates, a second locking element of this
kind equipped with an integrated damping element is also suitable
for use as a magnetic armature plate.
The second locking element can be axially guided in a particularly
simple fashion by having axial indentations formed into it that
engage with corresponding axial guide elements of the coil support
or inner pole of the electromagnet. As a result, no additional
components are required since the axial guide elements and
counterpart guide elements, respectively, can be integrally formed
onto the electromagnet and the second locking element.
It is advantageous to operate the locking device in such a way that
during the operating state, the at least one electromagnet is
activated so that it pulls the second locking element axially away
from the first locking element in opposition to a restoring force.
As a result, the drive shaft is able to rotate unhindered during
the powered state of the electromagnet. In the deactivated
(unpowered) state of the electromagnet, the contact force of the
return element then presses the second locking element against the
first locking element in order to prevent the rotary motion in the
locked state.
If the electromagnet pulls on the second locking element in the
rotatable state, then this causes the locking element to rest
against the damping element, which in turn rests against the
electromagnet. This avoids a resonance generation of acoustic
vibrations.
By forming a recess into the cylindrical wall embodied as the pole
tube of the electromagnet, on the side radially opposite from the
connector plug of the electromagnet, it is possible to produce a
uniform axial attraction of the second locking element over the
entire circumference. This prevents a tilting or jamming of the
second locking element during its actuation, thus causing it to
strike against the damping element with less impact, consequently
reducing the generation of noise.
If the locking device according to the present invention is built
into a transmission/drive unit, the first locking element rotates
with the shaft; the first locking element in both axial directions
on the locking device. In order to prevent a mutual contact between
the two locking elements, the first rotating locking element rests
against an axial side of the lock housing embodied in the form of a
thrust washer. To this end, the first locking element has axial
extensions that engage behind a thrust washer of the lock
housing.
The method according to the invention for manufacturing a
transmission/drive unit according to the invention has the
advantage that because the locking device is embodied separately,
it can simply be inserted into the housing together with the two
locking elements and mounted on the drive shaft without strict
tolerance requirements. To that end, the drive shaft is inserted
into a drive element that produces a form-locked engagement with
the first locking element in order to transmit torque. In a
particularly suitable embodiment, the locking device is installed
in the housing of the drive unit by being press-fitted into place
and then being axially secured through material shaping. The axial
positioning of the locking device here is not critical since the
distance between the two locking elements is adjusted by means of
the stops of the lock housing and drive shaft.
In order to manufacture the separately installable locking device,
it is particularly suitable to assemble the two locking elements
with the electromagnet, the return element, and the damping element
inside a lock housing, which can then in turn be simply installed
into the housing of the transmission/drive unit. The lock housing
in this case absorbs the forces acting on the locking device and
transmits them to the housing of the transmission/drive unit. If it
is embodied, for example, as approximately closed, then the lock
housing simultaneously protects the locking elements from dirt. The
complete preassembly of the locking device with the two locking
elements, the electromagnet, the at least one return element, and
the damping element permits a supplier to independently produce
this locking device, which is embodied in the form of a separate
component, and test its function and power consumption. This
significantly simplifies the assembly and function testing of the
transmission/drive unit.
DRAWINGS
Various exemplary embodiments of a locking device according to the
invention and of a transmission/drive unit are shown in the
drawings and explained in detail in the description that
follows.
FIG. 1 shows a section through a locking device according to the
invention, installed in a transmission/drive unit,
FIG. 2 is an axial view of the locking device from FIG. 1,
FIG. 3 shows a section through the locking device from FIG. 2 along
the line III-III,
FIG. 4 shows a section through another exemplary embodiment of a
locking device,
FIG. 5 shows another variation of the second locking element
according to FIG. 4,
FIG. 6 shows other damping elements according to the invention,
FIG. 7 shows another variation of a locking device, and
FIG. 8 shows another damping element according to the
invention.
DESCRIPTION OF THE EXEMPLARY EMBODIMENTS
FIG. 1 shows a transmission/drive unit 10 in which an electric
motor 12 with a drive shaft 14 is situated inside a housing 16 of
the transmission/drive unit 10. The drive shaft 14 is supported by
means of a roller bearing 18 and/or a slide bearing 20 and has a
worm 24 that cooperates, for example by means of a worm gear 22,
with an actuating element, not shown, of a moving part in the motor
vehicle. In order to lock the drive shaft 14 in relation to the
housing 16, a locking device 30 composed of a first locking element
32 and second locking element 34 is situated inside the housing 16.
The first locking element 32 engages in a form-locked fashion with
a drive element 66 that is supported in a rotationally fixed
fashion on the drive shaft 14. By contrast, the second locking
element 34 is attached in a rotationally fixed fashion to the
housing 16. In the locked state (as shown in FIG. 1), the first
locking element 32 engages in a form-locked fashion with the second
locking element 34, thus preventing a rotation of the drive shaft
14. To this end, the two locking elements 32, 34 have radially
extending flutes 82 and protrusions 84 that produce an axially
form-locked engagement 85 and are pressed into engagement with one
another in accordance with an axial gearing 85 by means of at least
one resilient return element 42. In the exemplary embodiment, the
surfaces of the locking elements 32, 34 that engage each other in a
form-locked manner are situated at an angle of less than 90.degree.
and greater than 90.degree., respectively, in relation to the shaft
14. The second locking element 34 is operatively connected to an
electromagnet 44, which, in the powered state, pulls the second
locking element 34 axially away from the first locking element 32
in opposition to the spring force of the return element 42 in such
a way that the axial form-locked engagement 85 is released and the
two locking elements 32 and 34 can rotate in relation to each other
without touching each other. The electromagnet 44 is supported in a
coil support 46 that on the one hand, is attached to the housing 16
in a rotationally fixed fashion and on the other hand, has axial
guide elements 78 that cooperate with corresponding axial
counterpart guide elements 80 of the second locking element 34.
This assures that when a current is applied to the electromagnet
44, the locking device 30 is in the rotatable state, whereas the
unpowered state corresponds to the locked state. In this instance,
the locking device 30 is a separate, preassembled component 31 that
includes at least the two locking elements 32, 34 and the
electromagnet 44. In FIG. 1, these components are situated in a
lock housing 52 of the locking device 30; the lock housing 52 is
press-fitted axially into the housing 16 and is prevented from
shifting. Between the second locking element 34 and electromagnet
44, at least one damping element 28 is provided, which prevents the
generation of unpleasant noise when the second locking element 34
strikes against electromagnet 44.
FIG. 2 shows a view of the separately embodied locking device 30 in
the axial direction before it is installed into the
transmission/drive unit 10. The two locking elements 32, 34 and the
electromagnet 44 are situated in the lock housing 52. The lock
housing 52 is cylindrically embodied and on its circumference has
detent elements 54 that dig into the housing 16 when inserted into
it. On the circumference of the lock housing 52, a plug element 58,
which can be supplied with current independently of the motor
current of the electric motor 12, is provided as an electrical
contacting point 56 of the electromagnet 44. The end surface of the
lock housing 52 is embodied as a thrust washer 60 against which the
first locking element 32 is axially supported by means of axial
extensions 62. The first locking element 32 is embodied as a disk
with a central opening 64, which engages in a form-locked fashion
with a drive element 66. In the exemplary embodiment, the
form-locked connection is composed of an internal gearing 68 of the
first locking element 32, which is slid axially onto an external
gearing 70 of the drive element 66. During assembly of the
transmission/drive unit 10 in this case, the drive element 66 is
first attached to the drive shaft 14 in a rotationally fixed
fashion and then the drive shaft 14 with the drive element 66 is
inserted axially into the opening 64 of the locking device 30.
Since the first locking element 32 is supported axially inside the
lock housing 52, the axial positioning of the drive shaft 14 is not
tolerance-sensitive to the locking device 30.
FIG. 3 shows a section through the locking device 30 from FIG. 2
along the line III-III; for the sake of illustration, the drive
element 66 is depicted without the drive shaft 14, in form-locked
engagement with the first locking element 32. At its central
opening 64, the first locking element 32 has a sleeve 72 onto which
the internal gearing 68 is formed. For axial support in relation to
the inner wall of the thrust washer 60, the locking element 32 has
an axial extension 62 in the form of a circumferential rib 63,
which rests against the rotationally fixed stop 74 formed by the
inner wall of the thrust washer 60. For support in relation to the
electromagnet 44, the first locking element 32 has additional axial
extensions 62 that are embodied in the form of detent hooks 61,
which reach through the central opening 64 of the thrust washer 60
and rest against the outer wall of the thrust washer 60 that
constitutes an additional stop 74. The detent hooks 61 are cut out
from the sleeve 72 so that they can be flexibly inserted through
the opening 64 and then snap securely into place. In this way, the
first locking element 32 is reliably secured against axial movement
inside the lock housing 52 in a simple fashion. In an alternative
embodiment that is not shown, the axial extensions 62 rest against
the outside of the thrust washer 60 by means of a material shaping
or the axial extensions 62 are embodied in the form of a dome that
is supported against the thrust washer 60 by means of a clamping
ring. The electromagnet 44 is situated on the coil support 46 that
simultaneously constitutes part of the lock housing 52. The second
locking element 34 is situated in a rotationally fixed fashion in
the lock housing 52 by means of axial guide elements 78; the guide
elements 78 cooperate with corresponding counterpart elements 80 of
the lock housing 52. In the locked state, the return element 42
presses the second locking element 34, which is embodied in the
form of a disk, into a form-locked engagement with the first
locking element 32. If the electromagnet 44 is supplied with
current, then the magnetic force pulls the locking element 34
downward in FIG. 3, as a result of which the form-locked engagement
85 of the locked state is released and the first locking element 32
is able to rotate frictionlessly in relation to the second locking
element 34. The return element 42 is composed, for example, of
several spring elements 43 or is embodied in the form of a uniform
spring element 43 that encompasses the central opening 64. The
damping element 28 is embodied in the form of a damping ring 86
made of plastic, in particular an elastomer, which in the installed
state, encloses the drive shaft 14. The damping ring 86 in this
case is fastened to the axial surface 88 of the second locking
element 34 oriented toward the electromagnet 44 or is fastened
directly to the electromagnet 44. To embody an axial form-locked
engagement 85 in the locked state, the locking elements 32 and 34
each have radially extending recesses 82 and raised regions 84 that
are embodied, for example, in the form of axial gearing 85.
FIG. 4 shows another exemplary embodiment of a locking device 30.
The coil support 46 of the electromagnet 44 is embodied in the form
of an inner pole 47 on which the coil element 45 is situated. The
lock housing 52 has a cylindrical wall 35 that is attached, for
example, to a separately embodied bottom surface 37 of the lock
housing 52, in particular by being swaged onto it. The inner pole
47, together with the bottom surface 37, the cylindrical wall 35,
and the second locking element serving as an armature plate 41,
constitutes a magnetic yoke for the coil element 45 of the
electromagnet 44. The second locking element 34 in this exemplary
embodiment is composed of a structure-borne noise-damping composite
plate 38 in which a plastic layer 39 is embedded between two metal
plates 40. The plastic layer 39 has a thickness of 0.01-0.1 mm, for
example, and is composed of a viscoelastic material that is adapted
to the specific geometry of the locking device 30 for
vibration-damping purposes. As a result, the composite plate 38
with the plastic layer 39 represents a damping element 28 that is
integrated into the second locking element 34. The axial
form-locked engagement/gearing 85 in this case is formed onto the
composite plate 38, for example is injection-molded out of plastic
that is formed directly onto the plate. The metal plates 40 have a
thickness of 0.1-2.0 mm, for example, and are preferably composed
of plate steel. In an alternative embodiment that is not shown
here, the composite plate 38 has only a single metal plate 40 and a
single plastic disk 39. In addition to the damping element 28
integrated into the second locking element 34, the locking device
30 has another damping element 28 that is embodied as a damping
ring 90 that damps in the axial direction. For example, the damping
ring 90 has a rectangular cross section 91 and is fastened in a
corresponding groove 92 of the metal inner pole 47. FIG. 4 shows a
state in which, with the electromagnet 44 powered, the locking
element 34 has just disengaged from the form-locked engagement 82,
84, but has not yet come to rest against the damping ring 90 of the
inner pole 47. The second locking element 34 is guided by the axial
guides 78, which are formed onto the coil element 45 in the form of
guide pins 79 and engage in corresponding counterpart guide
elements 80 in the form of axial holes 81 that are formed into the
second locking element 34. The return element 42, which is embodied
in the form of an annular spring element 43 that encompasses the
drive shaft 14, serves to reset the second locking element 34 in
order to lock the transmission. As in FIG. 3, the coil element 45
has a plug element 58 that axially engages in a corresponding
cut-out 93 of the second locking element 34. In order to balance
the magnetic flux, the cylinder wall 35 functioning as a pole tube
of the electromagnet 44 has a recess 76 that is intended to
compensate for the missing wall material of the cylinder wall 35
and/or of the second locking element 34 embodied in the form of an
armature plate 41, in the region of the plug 58.
FIG. 5 shows a disk-shaped base part 94 of the second locking
element 34 in accordance with the embodiment from FIG. 4. The base
part 94 is embodied in the form of the composite plate 38 on which
corresponding recesses 95 are provided for the molding-on of the
axial form-locked engagement 85. In addition, three holes 81 are
visible, which serve as counterpart guide elements 80 for
corresponding guide pins 79. In this embodiment, an annular plastic
film 96 is fastened as a damping element 28 onto the axial surface
88 of the second locking element 34. The plastic film 96 is
embodied, for example, as an adhesive film that adheres to the
axial surface 88 in a self-adhesive fashion and when pulled toward
the electromagnet 44, comes to rest against it. Such a damping
element 28 embodied in the form of a plastic film 96 is likewise
suitable for combination with a composite plate 38 in which another
damping element 28 is situated inside the base part 94 of the
second locking element 34. For the magnetic compensation or weight
compensation of the cut-out 93 of the second locking element 34, it
is optionally possible for corresponding sections 97 to be cut out
from the locking element 34--in particular on the radially opposite
side.
FIG. 6 shows another exemplary embodiment of a damping element 28,
which is embodied in the form of a hat-shaped cap 98 that rests
against the electromagnet 44. In relation to the coil element 45,
the inner pole 47 forms an axial offset 49 against which the
hat-shaped cap 98 rests in the radial direction. Oriented toward
the drive shaft 14, the inner pole 47 has an additional axial
extension 51; the hat-shaped cap 98 extends in the radial direction
all the way to this axial extension. The extension 51 optionally
also serves to axially guide and center of the second locking
element 34. An annular spring element 43 presses the cap 98 axially
against the electromagnet 44; the spring element 43 is
simultaneously embodied as a return element 42 of the second
locking element 34. The spring element 43 is embodied in the form
of a conical spiral spring 99 that in particular rests against the
cap 98 in the region of the axial offset 49. As a stop surface 100
for the axial surface 88 of the second locking element 34, the
hat-shaped cap 98 has a corresponding profiling 101 that can be
embodied in several variations according to FIG. 6 in order to
satisfy various damping requirements. For example, the profiling
101 here has a bead 103, an axial curvature 104, or several ribs
105. The cap 98 in the exemplary embodiment is made of Teflon, but
can as needed also be made of another noise-damping material, e.g.
HNBR. For improved contact of the hat-shaped damping element 98,
the axial side 87 of the electromagnet 44 is provided with a
structuring 102 (in particular flutes or bombardment) formed onto
it, which should increase the action of the damping element 28.
FIG. 7 shows another embodiment of a locking device 30 in an
intermediate position in which the damping element 28 is formed
directly onto the return element 42. The return element 42 is
embodied in the form of a spiral spring 99 with a plurality of
coils 114 that are pressed against the electromagnet 44 by the
second locking element 34 when the electromagnet 44 is switched on
(depicted with dashed lines). In the example, the damping element
28 is embodied in the form of an elastic sheath 112 around at least
one coil 114 so that when the locking device 30 is open, both the
second locking element 34 and the electromagnet 44 rest against the
elastic sheath 112--for example an extrusion coating with
elastomer, which therefore damps the impact. In order to precisely
adjust the braking path predetermined by the thickness 116 of the
damping element 28, the coil element 45 is situated against a
collar 108 of the inner pole 47 so that the tolerances for the
braking path are kept to a minimum. Between the first and second
locking element 32, 34, an additional damping element 29 is
provided, which damps the impact of the second locking element 34
against the first locking element 32 during the closing of the
lock. In the process of this, the damping element 29 that is
fastened to the first or second locking element 32, 34 comes to
rest against the opposing locking element 32, 34 before the
form-locked engagement 85 is completely achieved. Like the first
damping element 28, the additional damping element 29 can be
fastened by various means, for example by being glued, clipped, or
molded-on.
FIG. 8 shows another locking element 30 in which the damping
element 28 is embodied as a radius 110 formed onto the
electromagnet 44. The radius 110 is formed onto the axial end
surface 87 of the inner pole 47, for example, so that during the
opening of the lock, the second locking element 34 initially rests
with a relatively small radially inner region 118 against the
radius 110 and is then the elastically deformed in the axial
direction 15 (depicted with dashed lines) and comes to rest against
the electromagnet 44, following along the radius 110. This brakes
the axial impact of the second locking element 34, thus suppressing
the excitation of structure-borne noise.
It should be noted with regard to the exemplary embodiments shown
in the figures and disclosed in the description that there are a
multitude of possible combinations of the individual defining
characteristics with one another. It is thus possible, for example,
to vary the specific embodiment of the form-locked engagement 85
between the first and second locking elements 32, 34 and the
specific embodiment of the damping element 28 and spring element 43
and to adapt them to the requirements, in particular with regard to
vibration-, agitation-, and noise loads. Preferably, the
transmission/drive unit 10 according to the invention is used to
actuate a differential transmission of a vehicle that is subjected,
for example, to an agitation load of 20 g. The locking device 30
according to the invention can, however, also be used for other
electric motors 12 such as actuator drive units, which are
subjected to a high temperature- and vibration load.
* * * * *